The firebrand former mayor has been a worry for the country’s booming online gambling industry and in August scrapped one firm’s 13-year monopoly of gambling in licensed online cafes.

The Philippine gambling industry is one of Asia’s most freewheeling, attracting many online foreign companies over the last decade to set up servers aimed at overseas punters, and has lured investments of billions of dollars in casino resorts.

Duterte’s latest pledge came less than 24 hours after the United Nations human rights commission urged the Philippines to launch murder investigations into the president’s claims he killed three people as mayor of Davao City as well as probing all the killings in his war on drugs.

Since assuming the presidency in July, 6,000 people have been killed in the government’s drug campaign, about a third have died in police anti-narcotics operations and the rest by motorcycle-riding masked men and vigilante groups.

Duterte told a gathering of businessmen last week that as mayor of Davao City he “personally” killed criminals as he prowled the streets.

He later admitted killing three men, who were involved in a kidnapping case, during a police gunfight in late 1980s.

“The Philippines judicial authorities must demonstrate their commitment to upholding the law and their independence from the executive by launching a murder investigation,” said Zeid Ra’ad Al Hussein, UN High Commissioner for Human Rights, in reference to Duterte’s claims.

“The killing described by President Duterte also violates international law, including the right to life, freedom from violence and force, due process and fair trial, equal protection before the law and innocence until proven guilty,” Zeid said in a statement.